I met Marvin Steffensen, his daughters Tina and Kim, and Kim’s daughter Shannon: three generations of Iowans, all willing to come to a coffeehouse at 8 a.m. on Father’s Day and talk about their genes. They were all very gracious, but what struck me in particular was that Kim and Tina looked so different: Kim is blonde and big-boned with creamy skin, while Tina is tiny, fit, and tan, with darker hair—differences that are mostly genetic. Kim also eats meat, dislikes exercise, and is struggling to lose weight. Tina is a vegetarian and exercises a lot, but her cholesterol is still 250, the same as Kim’s. That’s the genetic lottery in a nutshell.

What was your worst experience during this assignment?

I’m kind of phobic about needles and feel nauseous when I have to get an injection. To get my heart workup at the Cleveland Clinic, I had vials of blood drawn three different times: once for the genetic screening and twice for the standard panel, where technicians measure a dozen chemical markers I’d never heard of but that are associated with a higher risk of atherosclerosis. It was worth it to learn that my numbers were in the safe zone. Given my father’s life of heart disease, it’s been a family worry since I was born.

What was the oddest experience that you encountered during this assignment?

Just to step in the room where angioplasties are done, you have to put on a lead apron, a full set of scrubs, sterile booties, a hair net, and plastic protective goggles—though I was allowed to carry my nonsterile notepad and pen. I’ve watched surgeries before, but never one where the patient was awake. The effect was like watching a split-screen TV. On one screen—in black and white—I could watch the wire being threaded through a two-foot-long (one meter) artery and into Gloria Stevens’s heart. At the same time, the doctor was making small talk with Gloria, asking about her family and children. That threading a balloon-wrapped wire into a person’s heart could feel so routine, it was one of those moments where modern medicine seemed genuinely remarkable.